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Timely herbicide applications for no-till soybean can be challenging given the diverse communities of both winter and summer annual weeds that are often present. Research was conducted to compare various approaches for nonselective and preplant weed control for notill soybean. Nonselective herbicide application timings of fall (with and without a residual herbicide) followed by early-spring (4 wk before planting), late-spring (1 to 2 wk before planting), or sequential-spring applications (4 wk before planting and at planting) were compared. Spring applications also included a residual herbicide. For consistent control of winter annual weeds, two herbicide applications were needed, either a fall application followed by a spring application or sequential-spring applications. When a fall herbicide application did not include a residual herbicide, greater winter annual weed control resulted from early- or sequential-spring treatments. However, application timings that effectively controlled winter annual weeds did not effectively control summer annual weeds that have a prolonged emergence period. Palmer amaranth and large crabgrass control at 4 wk after planting was better when the spring residual treatment (chlorimuron plus metribuzin) was applied 1 to 2 wk before planting or at planting, compared with 4 wk before planting. Results indicate that in order to optimize control, herbicide application programs in soybean should coincide with seasonal growth cycles of winter and summer annual weeds. Nomenclature: Chlorimuron; metribuzin; large crabgrass, Digitaria sanguinalis (L.) Scop.; Palmer amaranth, Amaranthus palmeri S. Watson; soybean, Glycine max (L.) Merr

The development of dicamba-tolerant and other auxin-tolerant crops will enable the use of these effective herbicides in soybean and cotton at application timings such as at planting or over-the-top that are not currently possible. This research examined the effect of various factors on detection of postapplication amounts of dicamba in the air under field conditions by coupling a sample collection system with advanced chemical analysis of those samples. The quantity of dimethylamine salt of dicamba that was detected within 48 hr after application was two times greater (P < 0.05) than the quantity of diglycoamine salt formulation based on field studies in 2009. Regardless of application timing, the amount of detected dicamba was greatest during the 0 to 12 hr time period after application. However, the total detected after 48 hr was less for evening applications (5 micrograms [µg]) compared with midday (17 µg) or morning (14 µg) applications based on 2010 field trials. Average ambient air temperature (and other weather variables) correlated with higher detection levels of dicamba in the air in the field. Nomenclature: Dicamba, soybean, Glycine max (L.) Merr.

As dicamba resistance traits become more common in agronomic crops, the potential for off-site movement also increases. Little is known of how common vegetable crops will respond to dicamba drift. The objective of this study was to evaluate the effect of dicamba and glyphosate drift on bell pepper and squash growth as a function of application timing. The treatments were arranged in a factorial design with two timings by three rates and a nontreated check. The two timings were early bloom and midbloom (during bloom when fruit were present). The three rates were glyphosate at 21 + dicamba at 14 g ha−1, glyphosate at 10 + dicamba at 7 g ha−1, and glyphosate at 7 + dicamba 5 at g ha−1. Herbicides were applied with a controlled droplet applicator calibrated to deliver 2.34 L ha−1. In squash, crop injury was 26 to 31% at 3 DAT and 48 to 65% at 17 DAT. However, no differences were measured among application timings or rates for fruit weight or number at individual harvest or season total. Bell pepper injury ranged between 0 and 8% from 3 to 17 DAT and was not significantly different than the nontreated. However, large, Fancy, marketable, and total bell pepper fruit number were greater in the nontreated than glyphosate at 21 + dicamba 14 at g ha−1 and glyphosate at 10 + dicamba at 7 g ha−1 both years. The three rates of dicamba + glyphosate had a greater number and weight of cull fruit compared to the number of fruit in the nontreated plots. The cull fruit were shorter with a flattened appearance. Leaving bell pepper fruit on the plants longer may result in small and medium fruit becoming large or Fancy grade bell pepper fruit. Nomenclature: Glyphosate; dicamba; bell pepper, Capsicum anuum L.; squash, Cucumis melo L. Al volverse más común la resistencia a dicamba en cultivos agronómicos, el potencial de movimiento del herbicida a lugares no deseados se incrementa. Se conoce poco de cómo responderán los cultivos de vegetales a la deriva de dicamba. El objetivo de este estudio fue evaluar el efecto de la deriva de dicamba y glyphosate en el crecimiento del pimiento y la calabaza en función del momento de aplicación. Los tratamientos fueron arreglados en un diseño factorial con dos momentos de aplicación y tres dosis y un testigo sin tratamiento. Los dos momentos de aplicación fueron floración temprana y floración media (durante la floración cuando hubo presencia de frutos). Las tres dosis fueron glyphosate a 21 + dicamba a 14 g ha−1, glyphosate a 10 + dicamba a 7 g ha−1, y glyphosate a 7 + dicamba a 5 g ha−1. Los herbicidas fueron aplicados con una aplicador con gota controlada y calibrado para liberar 2.34 L ha−1. En la calabaza, el daño al cultivo fue 26 a 31% a 3 DAT y 48 a 65% a 17 DAT. Sin embargo, no se midieron diferencias entre momentos de aplicación o dosis para el peso o número de frutos para cosechas individuales o para el total de la temporada. El daño en el pimiento varió entre 0 y 8% entre 3 y 17 DAT, y no fue significativamente diferente del testigo sin tratamiento. Sin embargo, el número de frutos grandes, Fancy, comercializables, y totales fue mayor en el testigo que con glyphosate a 21 + dicamba a 14 g ha−1 y glyphosate a 10 + dicamba a 7 g ha−1 en ambos años. Las tres dosis de dicamba + glyphosate tuvieron un mayor número y peso de fruto de rechazo al compararse con el número de frutos en las parcelas testigo. La fruta de rechazo fue más corta con una apariencia aplanada. El dejar el fruto del pimiento en las plantas por más tiempo podría hacer que frutos pequeños y medianos alcancen un tamaño grande o una categoría Fancy.

Dense populations of glyphosate-resistant (GR) Italian ryegrass are problematic for spring burndown herbicide programs and crop establishment in the midsouthern United States. Two field studies were conducted to evaluate fall-applied residual herbicides for control of GR Italian ryegrass and to identify the most effective application timing for these herbicides. Fall applications of clomazone at 0.84 and 1.12 kg ai ha−1, pyroxasulfone at 0.16 kg ai ha−1, and S-metolachlor at 1.79 kg ai ha−1 controlled GR Italian ryegrass ≥ 93% 180 d after application. Control from incorporated applications of pendimethalin at 1.59 kg ai ha−1 and trifluralin at 1.68 kg ai ha−1 and surface applications of S-metolachlor at 1.42 kg ha−1 provided control similar to the best treatments. Glyphosate-resistant Italian ryegrass control following clomazone, pyroxasulfone, S-metolachlor, or trifluralin applied in mid September, October, or November exceeded that from fall tillage by 19 to 56% at 90 and 140 d after the last treatment. Pyroxasulfone and S-metolachlor controlled more GR Italian ryegrass following October or November applications compared with those in September at both 90 and 140 d after the last application timing. However, the benefit of delaying clomazone application from October to November was not realized until the last evaluation (140 d after the last treatment). Clomazone, pyroxasulfone, and S-metolachlor offer growers the best opportunity for residual control of GR Italian ryegrass, and control is optimized when these herbicides are applied in November. Nomenclature: Clomazone; glyphosate; pendimethalin; pyroxasulfone; S-metolachlor; trifluralin; Italian ryegrass, Lolium perenne L. ssp. multiflorum (Lam.) Husnot. LOLMU. Poblaciones densas de Lolium perenne ssp. multiflorum resistente a glyphosate (GR) son problemáticas para los programas de eliminación de vegetación en la primavera y para el establecimiento de cultivos en el centro-sur de los Estados Unidos. Se realizaron dos estudios de campo para evaluar aplicaciones de herbicidas residuales en el otoño para el control de L. perenne GR y para identificar el momento de aplicación más efectivo para estos herbicidas. Aplicaciones en el otoño de clomazone a 0.84 y 1.12 kg ai ha−1, pyroxasulfone a 0.16 kg ai ha−1, y S-metolachlor a 1.79 kg ai ha−1 controlaron L. perenne GR ≥93%, 180 d después de la aplicación. El control a partir de aplicaciones incorporadas de pendimethalin a 1.59 kg ai ha−1 y trifluralin a 1.68 kg ai ha−1 y aplicaciones superficiales de S-metolachlor a 1.42 kg ha−1 brindaron un control similar a los mejores tratamientos. El control de L. perenne GR después de aplicaciones de clomazone, pyroxasulfone, S-metolachlor, o trifluralin, en la mitad de Septiembre, Octubre, o Noviembre, excedieron el control obtenido con labranza en el otoño en 19 a 56%, a 90 a 140 d después del tratamiento. Pyroxasulfone y S- metolachlor aplicados en Octubre o Noviembre controlaron L. perenne GR más que las aplicaciones en Septiembre a 90 y 140 d después del último momento de aplicación. Sin embargo, el beneficio de retrasar la aplicación de clomazone de Octubre a Noviembre no se vio sino hasta la última evaluación (140 d después del tratamiento). Clomazone, pyroxasulfone, y S-metolachlor ofrecen a los productores la mejor oportunidad de control residual de L. perenne GR, y el control se optimiza cuando estos herbicidas se aplican en Noviembre.

Macartney rose is an aggressive, thorny shrub that suppresses forage production and strongly hinders cattle grazing in southern pastures. Previous studies have found this weed to be extremely difficult to control with most pasture herbicides. We conducted two studies in central Alabama to assess several new herbicide chemistries applied at spring, early fall, and late fall timings. In the first study, we compared aminocyclopyrachlor, tank mixed with either 2,4-D, triclopyr, metsulfuron, or chlorsulfuron, with the commercial standard, picloram + 2,4-D. In the second study, we compared aminopyralid, tank mixed with either 2,4-D or metsulfuron and triclopyr + fluroxypyr, to the commercial standard, picloram + 2,4-D. Aminocyclopyrachlor + chlorsulfuron or metsulfuron and aminopyralid + 2,4-D or metsulfuron provided acceptable control and were comparable to picloram + 2,4-D at the early fall timing. Macartney rose control with treatments applied at the late fall timing tended to be less than commercially acceptable levels. We found that no herbicide treatment controlled Macartney rose at the spring timing. In addition, triclopyr + fluroxypyr did not control Macartney rose at any application timing. These results indicate that the early fall timing was optimal and that both aminocyclopyrachlor and aminopyralid can provide good Macartney rose control when mixed with certain other herbicides, including metsulfuron. Nomenclature: 2,4-D; aminocyclopyrachlor; aminopyralid; chlorsulfuron; fluroxypyr; metsulfuron; picloram; triclopyr; Macartney rose, Rosa bracteata J.C. Wendl ROSBC. Rosa bracteata es un arbusto espinoso agresivo que suprime la producción de forrajes e inhibe fuertemente el pastoreo del ganado en pastizales del sur. Estudios previos han encontrado que esta maleza es extremadamente difícil de controlar con la mayoría de los herbicidas para pastos. Nosotros realizamos dos estudios en el centro de Alabama para evaluar varios herbicidas químicos nuevos, aplicados en la primavera, temprano en el otoño, y tarde en el otoño. En el primer estudio, comparamos con el estándar comercial, picloram + 2,4-D aplicaciones de aminocyclopyrachlor, mezclado ya fuese con 2,4-D, triclopyr, metsulfuron, o chlorsulfuron. En el segundo estudio, comparamos aminopyralid, mezclado en tanque con ya fuese 2,4-D o metsulfuron y triclopyr + fluroxypyr, con el estándar comercial, picloram + 2,4-D. Aminocyclopyrachlor + chlorsulfuron o metsulfuron y aminopyralid + 2,4-D o metsulfuron brindaron un control aceptable y fueron comparables con picloram + 2,4-D para aplicaciones temprano en el otoño. El control de R. bracteata con tratamientos aplicados tarde en el otoño tendió a ser inferior a los niveles comercialmente aceptables. Encontramos que ningún tratamiento con aplicaciones de herbicidas en la primavera controló R. bracteata. Adicionalmente, triclopyr + fluroxypyr no controló R. bracteata en ningún momento de aplicación. Estos resultados indican que temprano en el otoño fue el momento de aplicación óptimo y que tanto aminocyclopyrachlor como aminopyralid pueden brindar buen control de R. bracteata cuando se mezclan con otros herbicidas incluyendo metsulfuron.

Sicklepod and pitted morningglory are two of the most important weed species in row-crop production in the southeastern United States. The upcoming introduction of soybean and cotton varieties resistant to 2,4-D and dicamba will increase the reliance on these auxinic herbicides. However, it is not clear how these herbicides will affect sicklepod and pitted morningglory control. Field experiments were conducted in 2013 and 2014 in Jay, FL to determine whether 2,4-D (560 and 1,120 g ae ha−1), dicamba (420 and 840 g ae ha−1), and glyphosate (1,060 g ae ha−1) alone or in combination applied when weed shoots were 11 (early POST [EPOST]) and 22 (late POST [LPOST]) cm long effectively control and prevent seed production of sicklepod and pitted morningglory. LPOST provided more effective control of sicklepod than EPOST. This was attributed to emergence of sicklepod seedlings after the EPOST application. When glyphosate was tank mixed with 2,4-D or dicamba, sicklepod control was higher (78 to 89% and 87 to 98% in 2013 and 2014, respectively) than for single-herbicide treatments (45 to 77% and 38 to 80% in 2013 and 2014, respectively) 6 wk after treatment (WAT). Pitted morningglory control was not affected by application timing, and 2,4-D provided 91 to 100% 6 WAT, which was equivalent to treatments with tank mixtures containing glyphosate. Dicamba applied at 420 g ha−1 had the lowest pitted morningglory control (44 to 70% and 82 to 86% in 2013 and 2014, respectively). Sicklepod and pitted morningglory plants that survived and recovered from herbicide treatments produced the same number of viable seeds as nontreated plants in most treatments. The results of the present study indicated that the use of 2,4-D and dicamba alone will not provide adequate extended control of sicklepod, and the use of tank mixtures that combine auxinic herbicides with glyphosate or other POST herbicides will be necessary to manage sicklepod adequately in 2,4-D- or dicamba-resistant soybean and cotton. Because sicklepod plants that survived a single herbicide application are capable of producing abundant viable seeds, integrated approaches that include PRE herbicides and sequential POST control options may be necessary to ensure weed seed bank reductions. Nomenclature: 2,4-D; dicamba; glyphosate; pitted morningglory, Ipomoea lacunosa L. IPOLA; sicklepod, Senna obtusifolia (L.) H.S. Irwin & Barneby CASOB. Senna obtusifolia e Ipomoea lacunosa son dos de las especies de malezas más importantes en la producción de cultivos en hileras en el sureste de los Estados Unidos. Próximamente, la introducción de variedades de soja y algodón resistentes a 2,4-D y dicamba aumentará la dependencia en estos herbicidas auxínicos. Sin embargo, no está claro cómo estos herbicidas afectarán el control de S. obtusifolia e I. lacunosa. En 2013 y 2014, se realizaron experimentos de campo en Jay, FL para determinar si 2,4-D (560 y 1,120 g ae ha−1), dicamba (420 y 840 g ae ha−1), y glyphosate (1,060 g ae ha−1) solos o en combinación, aplicados cuando la parte aérea de las malezas alcanzó 11 (POST temprana [EPOST]) y 22 (POST tardía [LPOST]) cm de largo, controlan efectivamente S. obtusifolia e I. lacunosa y previenen la producción de semilla. LPOST brindó un control más efectivo de S. obtusifolia que EPOST. Esto fue atribuido a la emergencia de plántulas de S. obtusifolia después de la aplicación EPOST. Cuando glyphosate fue mezclado en tanque con 2,4-D o dicamba, el control de S. obtusifolia fue superior (78 a 89% y 87 a 98% en 2013 y 2014, respectivamente) que tratamientos con un solo herbicida (45 a 77% y 38 a 80% en 2013 y 2014, respectivamente) 6 semanas después del tratamiento (WAT). El control de I. lacunosa no fue afectado por el momento de aplicación, y 2,4-D brindó 91 a 100% de control 6 WAT, lo cual fue equivalente a los tratamientos con mezclas en tanque que contenían glyphosate. Dicamba aplicado a 420 g ha−1 tuvo el menor control de I. lacunosa (44 a 70% y 82 a 86% en 2013 y 2014, respectivamente). Las plantas de S. obtusifolia e I. lacunosa que sobrevivieron y se recuperaron de los tratamientos de herbicidas produjeron el mismo número de semillas viables que las plantas sin tratamiento en la mayoría de los tratamientos. Los resultados del presente estudio indicaron que el uso de sólo 2,4-D y dicamba no brindará un control adecuado extenso de S. obtusifolia, y el uso de mezclas en tanque que combinen herbicidas auxínicos con glyphosate u otros herbicidas POST será necesario para manejar adecuadamente S. obtusifolia en soja y algodón resistentes a 2,4-D o dicamba. Debido a que las plantas de S. obtusifolia que sobrevivieron a aplicaciones sencillas de herbicidas son capaces de producir una abundante cantidad de semillas viables, estrategias integradas que incluyan herbicidas PRE y seguidos de opciones de control POST podrían ser necesarias para asegurar reducciones en el banco de semillas de malezas.

Indaziflam is an alkylazine herbicide that controls annual grasses by inhibiting cellulose biosynthesis. Compared with other PRE herbicides like prodiamine, indaziflam has a longer half-life in soil (> 150 d), which may allow for greater flexibility with application timing. Research was conducted in 2010 in Tennessee and Georgia evaluating smooth crabgrass control efficacy with indaziflam applied at early PRE, PRE, and early POST timings on the basis of soil temperature. Regardless of application timing, all rates of indaziflam (35, 52.5, and 70 g ai ha−1) controlled smooth crabgrass 89 to 100%. Prodiamine at 840 g ai ha−1 applied PRE provided ≥ 99% smooth crabgrass control on all rating dates. Smooth crabgrass plant counts were significantly correlated (r  =  −0.961; p < 0.0001) with visual ratings of smooth crabgrass control at the end of the study. Application flexibility with indaziflam may benefit turf managers in scheduling herbicide applications for smooth crabgrass control in Tennessee and Georgia. Nomenclature: Indaziflam; prodiamine; smooth crabgrass [Digitaria ischaemum (Schreb.) Schreb. ex Muhl.].

Vaseygrass is an invasive, perennial C4-grass commonly found on roadsides in areas with poorly drained soils. Due to its upright growth habit and seedhead production, vaseygrass can impair motorist sightlines and subsequently, require increased management inputs to maintain vegetation at an acceptable height. Two field experiments were conducted from 2012 to 2015 on North Carolina roadsides to evaluate the effect of mowing and mowing timing with respect to applications of various herbicides on vaseygrass control. Both experiments evaluated clethodim (280 g ai ha−1), foramsulfuron+halosulfuron+thiencarbazone-methyl (44+69+22 g ai ha−1), imazapic (140 g ai ha−1), metsulfuron+nicosulfuron (16+59 g ai ha−1), and sulfosulfuron (105 g ai ha−1) with a nonionic surfactant at 0.25% v/v. Experiment one focused on the effect of mowing (routinely mowed or nonmowed) and herbicide application timing (fall-only, fall-plus-spring, or spring-only), while experiment two focused on pre-herbicide application mowing intervals (6, 4, 3, 2, 1, or 0 wk before treatment [WBT]). From experiment one, routine mowing reduced vaseygrass cover in nontreated plots 55% at 52 wk after fall treatment (WAFT), suggesting this cultural practice should be employed where possible. Additionally, routine mowing and herbicide application season affected herbicide efficacy. Treatments providing >70% vaseygrass cover reduction at 52 WAFT included routinely mowed fall-only clethodim and fall-plus-spring imazapic, and fall-plus-spring metsulfuron+nicosulfuron across mowing regimens. Within clethodim, mowing vaseygrass 2 or 1 WBT resulted in the lowest cover at 40 (1 to 2%) and 52 (4 to 6%) wk after treatment (WAT) compared to other intervals, which aligns with current label vegetation height at treatment recommendation. Vaseygrass persisted across all treatments evaluated through 52 WAT, suggesting eradication of this species will require inputs over multiple growing seasons. Nomenclature: Clethodim; foramsulfuron; halosulfuron; imazapic; metsulfuron; nicosulfuron; sulfosulfuron; thiencarbazone; vaseygrass, Paspalum urvillei Steud. Paspalum urvillei es una gramínea C4 perenne invasiva que se encuentra comúnmente a las orillas de caminos y en áreas con suelos con poco drenaje. Debido a su hábito de crecimiento vertical y producción de espigas, P. urvillei puede limitar la visibilidad de vehículos y subsecuentemente incrementar los insumos de manejo para mantener la vegetación a una altura aceptable. Se realizaron dos experimentos de campo desde 2012 a 2015 en orillas de caminos en North Carolina para evaluar los efectos de la chapia y el momento de chapia con respecto a las aplicaciones de varios herbicidas sobre el control de P. urvillei. Ambos experimentos evaluaron clethodim (280 g ai ha−1), foramsulfuron+halosulfuron+thiencarbazone-methyl (44+69+22 g ai ha−1), imazapic (140 g ai ha−1), metsulfuron+nicosulfuron (16+59 g ai ha−1), y sulfosulfuron (105 g ai ha−1) con un surfactante no iónico a 0,25% v/v. El experimento uno se enfocó en el efecto de la chapia (chapia rutinaria o sin chapia) y el momento de aplicación de herbicidas (sólo otoño, otoño más primavera, o sólo primavera), mientras que el experimento dos se enfocó en el intervalo entre la chapia y la aplicación de herbicidas (6, 4, 3, 2, 1, ó 0 semanas antes del tratamiento [WBT]). En el experimento uno, la chapia rutinaria redujo 55%la cobertura de P. urvillei en parcelas sin tratamiento con herbicidas a 52 semanas después del tratamiento de otoño (WAFT), sugiriendo que esta práctica cultural debería ser empleada cuando sea posible. Adicionalmente, la chapia rutinaria y la temporada de aplicación de herbicida afectaron la eficacia del herbicida. Los tratamientos que proveyeron >70% de reducción en la cobertura de P. urvillei a 52 WAFT incluyeron chapia rutinaria y clethodim sólo en el otoño e imazapic en el otoño más la primavera, y metsulfuron+nicosulfuron en el otoño más la primavera para todos los regímenes de chapia. Dentro de los tratamientos con clethodim, la chapia 2 ó 1 WBT resultó en la menor cobertura a 40 (1 a 2%) y 52 (4 a 6%) semanas después del tratamiento (WAT) al compararse con otros intervalos, lo que se alinea con la actual recomendación de la etiqueta de tratamiento según la altura de la vegetación. P. urvillei persistió en todos los tratamientos evaluados hasta 52 WAT, lo que sugiere que la erradicación de esta especie requerirá insumos a lo largo de múltiples temporadas de crecimiento.

Purple and yellow nutsedge are problematic weeds in Florida small fruit and vegetable production. EPTC and fomesafen are PRE herbicides that suppress both nutsedge species, but field application in Florida has shown control to be erratic. Greenhouse experiments were conducted in Gainesville, FL, from May to August 2014 and in Wimauma, FL, from March to May 2015 to investigate susceptibility of purple and yellow nutsedge to EPTC and fomesafen applications. Treatments included EPTC at 2.91 kg ai ha−1 and fomesafen at 0.42 kg ai ha−1 at 0, 3, 6, 9, 12, and 15 d after planting (DAP) tubers, plus a nontreated control. EPTC and fomesafen applications averaged across timings decreased purple and yellow nutsedge emergence, shoot height, leaf number, and shoot mass compared to the nontreated control. Herbicide applications 0 DAP reduced purple nutsedge emergence greater than 65% compared to the nontreated control and caused at least 74% injury 4 wk after planting. Herbicide applications 0 DAP decreased yellow nutsedge emergence and shoot mass compared to the nontreated control by at least 86 and 93%, respectively. Applications of EPTC and fomesafen have the ability to suppress short-term purple and yellow nutsedge growth. Applications made at or prior to tuber sprouting maximize herbicide efficacy. Nomenclature: EPTC; fomesafen; purple nutsedge, Cyperus rotundus L.; yellow nutsedge, Cyperus esculentus L.

Two experiments were conducted in 2015 at multiple locations in Florida to evaluate the effects of planting depth and application timing on S-metolachlor injury in sesame. In both studies, sesame responded negatively to increases in S-metolachlor rate. Altering sesame planting depth did not provide increased safety to PRE S-metolachlor applications. Sesame establishment declined with increased planting depth, likely because of the physical inability of the small seed to emerge from the 3.8-cm depth. Delaying applications of S-metolachlor by 3 or 6 d after planting (DAP) consistently improved sesame establishment. Applications 3 and 6 DAP resulted in 89 to 92% seedling emergence at 2 wk after planting (WAP), relative to 55 to 63% emergence when S-metolachlor was applied the day of planting (0 DAP) or 3 days before (−3 DAP), respectively. Applications 3 DAP resulted in 21 and 2% plant stunting when evaluated 3 and 6 WAP, respectively, whereas all other timings caused 25 to 51% stunting. Yield was reduced 22 and 33% by the −3 DAP and 0 DAP application timings, respectively, whereas no reduction in yield was observed by the delayed application timings. Therefore, delaying applications of S-metolachlor by 3 to 6 days will likely result in improved sesame seedling establishment and total seed yield. Nomenclature: S-metolachlor; sesame, Sesamum indicum L. ‘S38’.